1. Field of the Invention
This invention relates, in general, to motor vehicle fuel systems and, more specifically, to vapor and/or fuel seals for motor vehicle fuel systems.
2. Description of the Prior Art
In order to operate motor vehicles having internal combustion engines, such as automobiles, boats, airplanes, etc., the vehicle must have a steady supply of a combustible fuel such as gasoline, kerosene, diesel fuel, etc. typically, this fuel is stored in an on-board storage tank. The fuel can be introduced into the tank present on such vehicles from a supply reservoir through a dispensing nozzle.
As is readily appreciated, the fuels necessary to effectively operate internal combustion engines are generally present as liquids. However, these fuels are highly volatile and produce a significant amount of gaseous vapors at ambient temperatures. Transfer of engine fuel from supply reservoirs to the on-board storage tanks permits escape of some of the volatile vapors, allowing them to be introduced into the atmosphere. Such vapors contribute to the pollution of the overall atmosphere and, also, may cause harmful effects on the person dispensing the fuel if inhaled.
As can readily be appreciated, the fuels, whether in a gaseous or liquid state, are highly flammable. The potential exists for easy ignition of the vapor portion of these fuels if that portion is brought into contact with a flame or hot surface. This can potentially cause a vapor flashback, igniting larger liquid portions of the fuel in the reservoirs or on-board storage tank.
Furthermore, engine fuels are generally dispensed from a supply reservoir through a dispensing nozzle inserted into a filler inlet located in or connected to the on-board storage tank. Because the fuel is introduced at a relatively rapid rate, there exists a danger that the storage tank may overflow through the inlet opening and connected filler tube if the tank is overfilled. Additionally, certain tank configurations can also cause "burping"; a condition whereby small portions of the liquid fuel are expelled back through the filler tube and on-board storage tank inlet due to the presence of trapped air in the on-board storage tank. This expelled fuel can potentially get on operator's hands, be spilled down the side of a car marring its paint, and spill on to the ground, either contaminating the ground or evaporating and contributing to air pollution.
Efforts have been made to prevent the discharge of such vapors or liquid fuel into the environment by providing various seals which prevent the escape of engine fuel vapors. Typically, such sealing means are flexible caps attached to the dispensing nozzle of a storage tank. The flexible cap covers the end of the filler tube on the vehicle when the dispensing nozzle is inserted therein. While reducing the amount of vapors introduced into the atmosphere during the fuel transfer process, such sealing methods do not provide complete sealing of the filler tube. Even with these measures, significant amounts of fuel vapors still escape during the filling process. Furthermore, such sealing means do not prevent the escape of liquid fuel from the filler tube if the tank is inadvertently overfilled or filled at too fast a rate.
Various other types of vapor seals for fluid transfer processes are also known. In U.S. Pat. No. 3,903,942, an adaptor is mounted within the filler tube on a vehicle. The adaptor expands to sealingly receive the discharge end of the dispensing nozzle, preventing the escape of vapors from the vehicle tank during the fuel transfer process. This adaptor is provided with open inlet and outlet ends such that, when the adaptor is not being used for the introduction of fuel into the tank, the passage between the inlet and outlet remains open thereby allowing the escape of vapors and/or liquid fuel from the vehicle tank into the atmosphere upon removal of the filler tube cap.
Thus, it would be desirable to provide a vapor/fuel seal for a vehicle fuel filler tube which completely seals the inlet to the filler tube during use of the vehicle and, provides a seal when a dispensing nozzle from a storage tank is introduced into the filler tube during the transfer of fuel. It would also be desirable to provide a vapor/fuel seal for a fuel tank filler tube which may be easily installed on new and existing vehicles to provide the desired vapor and fuel sealing features described above.